3-5 August

Outcome: Ignore the rain; this was another nice fall


After initial heavy rain over the weekend (1-2 August; total about 70 mm at Perisher Valley), this was another decent fall — around 30 cm aggregate snowfall over the three days, right across the alps:


JAXA precipitation inferred from satellite imagery

BOM surface chart archive

Update #3 (31 July):

This one now has the standard two phases: Sunday isn’t looking as strong as it did; probably there’ll be some marginal rain / wet snow during the day, shifting to snow in the late evening / Monday morning — perhaps only 10 cm in total. But then there’s Wednesday, which is looking very interesting indeed (30 cm??):

ECMWF precipitation for Monday morning

ECMWF for Wednesday

Update #2 (28 July):

There’s not much doubt now that this system will arrive a day earlier than I had, so I’ve shifted the dates backwards a day. It still looks like a powerful system, though with the deep low tracking a long way south. The European ECMWF model is currently showing a particularly nice south-westerly fetch. There’s still time for things to change a bit of course.

(Note the tropical low near the Solomon Islands, again. Despite reports, tropical cyclone Raquel earlier this month was probably not the first in our region in July, though it does appear to have been the first named July cyclone. But a cyclone in August … that would be absurd.)

GFS for Monday, 3 August (Levi Cowan)

ECMWF for Monday (Levi Cowan)

Update #1 (23 July):

This is still solidly on track. The models have it arriving about a day earlier than I do, but remember that all our models seem to advance winter systems just a touch too quickly*.


(*That’s an emergent behavior from highly complex models of atmospheric physics. The models don’t have a “system advance speed” knob, otherwise it would have been twiddled long ago.)

Original post (20 July)

Sure, this is an out-there call, but the last couple seem to have gone OK. More snow weather is showing in the first week of August (click the chart for an explanation and the source link).

Part of my purpose is to demonstrate that with the current state of computer modelling, you really can make useful and skillful 2-week forecasts … at least once the seasonal weather patterns have settled in (a couple of my June efforts this year weren’t so great). Those who would scoff should have a look at the record last year.


1 comment to 3-5 August

  • Warrie

    But if the models are known to be running ahead of reality i. e. this emerged behaviour has been recognised for a while then why not a system retard speed knob? PS a 3cm gain this week must leading to some nerves re 140 cm peak. LOL…. W